How to Fix Outlook Data File Corruption Error: Step-by-Step Guide to Repair Corrupted Outlook Data Files

Experiencing “Outlook Data File Corruption” error causing Outlook to close? Learn how to fix persistent OST file issues and repair corrupted data files effectively.

Microsoft Outlook is a vital tool for millions of users managing their emails, contacts, calendars, and tasks daily. However, encountering an Outlook data file corruption error can disrupt productivity by preventing access to important information. This issue often causes Outlook to crash, freeze, or display error messages that stop you from opening your mailbox.

In this detailed guide, we will walk you through the meaning of Outlook data file corruption, the common causes behind it, and step-by-step solutions to fix corrupt Outlook PST and OST files. We’ll also explain the differences between PST and OST files, offer advice on how to troubleshoot Outlook file errors, and explore ways to open corrupted Outlook data files without Outlook itself. Our goal is to equip you with the knowledge and tools to resolve these problems efficiently and prevent future occurrences.

What Is Outlook Data File Corruption Error?

Outlook data files are essential for storing your mailbox data on your local machine. These files contain emails, contacts, calendar events, notes, tasks, and other Outlook items. There are two main types of Outlook data files:

OST (Offline Storage Table) files: Used by Microsoft Exchange, Microsoft 365, IMAP, and Outlook.com accounts, OST files store a synchronized offline copy of your mailbox. This allows you to work offline and have changes synced automatically when reconnected to the server.
PST (Personal Storage Table) files: Used primarily by POP accounts and for archiving purposes, PST files store all mailbox data locally without synchronization with a server.

When these files become corrupted, Outlook experiences difficulties reading or writing data, leading to errors, crashes, and loss of access to emails or other items.

Common Symptoms of Outlook Data File Corruption

Recognizing corruption early can prevent data loss. Symptoms include:

Outlook crashing unexpectedly.
Receiving error messages such as “Cannot open Outlook data file” or “Errors have been detected in the file Outlook OST/PST.”
Outlook not opening after restarting.
Inability to access specific folders or mailbox data.
The appearance of folders like “Recovered Personal Folders” or “Lost and Found” after repair attempts.
Synchronization failures or error messages during mail retrieval.

If you encounter any of these, it’s a strong indication of Outlook PST or OST corruption.

What Causes Outlook Data File to Become Corrupted?

Several factors contribute to Outlook data file corruption. These causes are broadly divided into hardware-related and software-related issues.

Hardware-Related Causes

1. Unstable or Poor Network Connection:

OST files synchronize mailbox data with the mail server. If the connection drops or is unstable during this process—especially when the OST file is stored on a network drive—file corruption may occur. This is also true for PST files located on network paths.

2. Hard Drive Malfunctions and Bad Sectors

Physical damage, mechanical failure, or logical errors on your hard drive can corrupt the files it stores. Bad sectors—areas of the hard disk that are damaged—are a common culprit. When Outlook data files are saved in these bad sectors, frequent corruption and performance degradation can result.

You can detect bad sectors by using specialized disk diagnostic tools like MiniTool Partition Wizard or Windows’ built-in chkdsk utility. For detailed guidance on managing disks and running disk diagnostics from the command prompt, see our comprehensive guide: Mastering Disk Management: How to Run Disk Manager from Command Prompt Like a Pro. Shielding or repairing these sectors or replacing the faulty hard drive is crucial to preventing further data corruption.

3. Sudden Power Loss or Improper Shutdown

Unexpected power outages or forcibly shutting down your computer while Outlook is running can interrupt the writing of data to OST or PST files, leading to corruption. Similarly, improperly terminating Outlook by force-quitting or through task manager can damage associated data files.

Software-Related Causes

1. Virus or Malware Infection

Malicious software can overwrite, delete, or otherwise damage Outlook data files. Without a reliable antivirus program running, the risk of PST or OST corruption increases significantly.

2. Oversized Data Files

Every Outlook data file has a maximum recommended size limit—typically 50GB for OST files in Outlook 2020 and newer. When these limits are exceeded, Outlook’s performance degrades, and the file becomes prone to corruption.

Regularly archiving old emails and managing mailbox size can help maintain data file integrity.

3. Incompatible or Faulty Outlook Add-ins

Third-party add-ins and plugins often enhance Outlook functionality, but some can cause conflicts or performance issues. Incompatible or poorly designed add-ins might slow down Outlook or trigger file corruption errors.

4. Issues Within Outlook Itself

Bugs, glitches, or failed updates in Microsoft Outlook can lead to data file issues. Sometimes the software creates inconsistencies in the OST or PST file formats, which can only be addressed via patches or repairs from Microsoft.

OST vs PST File Differences

Understanding the distinctions between OST and PST files will guide you in applying the correct repair method.

Feature	OST File	PST File
Accounts	Microsoft Exchange, Microsoft 365, IMAP, Outlook.com	POP accounts, archived data
Purpose	Stores synchronized offline copy of mailbox	Stores local mailbox data without synchronization
Synchronization	Syncs with mail server automatically	No synchronization
Location	Managed and hidden by Outlook	User-accessible
Repair Method	Can be deleted and recreated; third-party tools for recovery	Repair using ScanPST.exe or third-party tools

How to Repair a Corrupt Data File in Outlook?

Several solutions are available to repair corrupted Outlook PST or OST files, depending on the file type and severity of corruption.

1. Use Inbox Repair Tool (ScanPST.exe) to Repair PST Files

Microsoft provides the Inbox Repair Tool (ScanPST.exe) as a built-in utility to diagnose and repair corrupt PST files.

How to Use ScanPST.exe

Exit Outlook before starting the repair.
Locate ScanPST.exe on your PC. Its typical locations vary by Outlook version:
- Outlook 2019/2016: C:\Program Files (x86)\Microsoft Office\root\Office16
- Outlook 2013: C:\Program Files (x86)\Microsoft Office\Office15
- Outlook 2010: C:\Program Files (x86)\Microsoft Office\Office14
Open ScanPST.exe.
Click Browse and select the corrupted .pst file. To locate your PST file, check in Outlook under File > Account Settings > Data Files.
Click Start to scan the file for errors.
If errors are detected, choose Repair to fix them.
Once repair is complete, launch Outlook and verify if the issue is resolved.

Important Notes:

ScanPST creates a backup .bak file before repairing.
Sometimes multiple runs are required.
The repair process may create a Recovered Personal Folders or Lost and Found folder containing recovered items that could not be placed in their original locations.
If necessary, you can import items from the .bak file by renaming it to .pst and importing it into Outlook.

Using ScanPST.exe is often the most straightforward and effective way to resolve corrupt Outlook PST file issues.

2. Delete and Recreate OST File for Exchange and Microsoft 365 Accounts

Since OST files are synchronized copies of server data, corrupted OST files can often be fixed by deleting the existing OST and letting Outlook recreate it.

Steps to Delete and Recreate OST File

Close Outlook.
Open Outlook and go to File > Account Settings > Account Settings > Data Files.
Select the OST file, then click Open File Location.
Close Outlook completely.
Delete the OST file.
Restart Outlook. It will automatically rebuild the OST file by synchronizing mailbox data from the server.

This method resolves Outlook OST corruption without data loss, assuming server data is intact.

3. Disable Incompatible or Faulty Outlook Add-ins

Add-ins can cause Outlook to crash or corrupt data files.

To disable add-ins:

Start Outlook in Safe Mode by holding the Ctrl key while launching or running outlook.exe /safe via the Run dialog.
Go to File > Options > Add-ins.
At the bottom, next to Manage, select COM Add-ins and click Go.
Uncheck all add-ins and restart Outlook normally.
Enable add-ins one at a time to identify the problematic add-in causing issues.

4. Create a New Outlook Data File

When corruption is severe or persistent, creating a new Outlook data file and reconfiguring your mailbox can help.

How to create a new data file:

Close Outlook.
Open Control Panel > Mail > Data Files.
Select the corrupted data file and click Open File Location.
Move or rename the corrupted file as a backup.
Restart Outlook to create a new data file automatically.
Reconnect your account to sync data from the server.

This approach is particularly effective when the original data file cannot be repaired.

5. Use Third-Party Outlook Data File Repair Software

If built-in tools like ScanPST fail to fix the problem or if you want to recover unsynchronized data from a corrupted OST file, consider reliable third-party Outlook data file repair software. These tools often provide advanced recovery options and can handle more severe corruption.

Be sure to choose reputable software with positive user reviews and expert recommendations.

Outlook Keeps Saying Data File Is Corrupted — How to Fix?

If Outlook persistently reports that your data file is corrupted, try the following methods to resolve the issue:

Turn Off Cached Exchange Mode: Disable Cached Exchange Mode to access your mailbox directly online. This can help bypass any issues caused by the local OST cache file. To do this:

Go to File > Account Settings > Account Settings.
Select your email account and click Change.
Uncheck Use Cached Exchange Mode.
Restart Outlook and check if the error persists.

Archive Old Mailbox Data or Delete Unnecessary Items: Large mailbox sizes often contribute to file corruption. Archiving old emails or deleting unnecessary items helps reduce the size of your mailbox and data files.

Compact the OST File: Reducing the OST file size can improve Outlook performance and minimize corruption risk. To compact the OST file, follow these steps:

Open Outlook and go to File > Account Settings > Account Settings.
Click on the Email tab, then select More Settings.
Navigate to the Advanced tab.
Click on Outlook Data File Settings.
Choose Compact to reduce the file size.

Additionally, keep your Outlook and Windows updated, run antivirus scans to rule out malware, repair your Office installation if needed, and regularly back up your data to avoid data loss.

How to Open Corrupted Outlook Data File Without Outlook

Sometimes Outlook won’t open a corrupted data file despite repair efforts. In such cases, you can:

Use specialized PST repair tools that allow opening and extracting mailbox data without Outlook.
Import backup files created during ScanPST repair (.bak files) by renaming them with a .pst extension.
Convert OST files to PST format using dedicated OST to PST converter software to recover unsynchronized emails and contacts.

These methods offer alternative ways to recover critical data when Outlook itself is unresponsive.

Additional Tips to Prevent Outlook Data File Corruption

Prevention is always better than cure. To reduce the risk of Outlook data file corruption, follow these best practices:

Keep Outlook and Windows updated to benefit from the latest fixes and security patches.
Manage mailbox size by archiving old emails and deleting unnecessary items to avoid oversized files.
Use reputable antivirus software to protect against malware infections.
Always close Outlook properly and avoid force-quitting the application.
Limit add-ins to trusted ones and remove those you don’t need.
Backup your Outlook data files regularly so you can restore them if corruption occurs.

Conclusion: Solution for Outlook Data File Corruption Error

Outlook data file corruption can cause frustrating disruptions but is often resolvable using Microsoft’s built-in tools and best practices. Whether you are facing a corrupt Outlook PST file or an OST file corruption, solutions such as the Inbox Repair Tool (ScanPST.exe), deleting and recreating OST files, disabling add-ins, or creating new data files provide effective recovery options.

For stubborn or severe corruption, professional repair software or Microsoft Support may be necessary. Maintaining a clean system, stable network, and regular backups helps protect your Outlook data from future corruption.

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